1. Field of the Invention
The present invention relates to a zoom lens system suitable for a compact camera using a solid-state imaging device such as a CCD and in particular to a zoom lens system having a four-lens-group configuration of a positive-negative-positive-positive power arrangement.
2. Related Background Art
As a zoom lens system suitable for a solid-state imaging device such as a CCD, a zoom lens system constructed by a four-lens-group lens system having a lens group with positive refractive power disposed to the most object side has been disclosed in Japanese Patent Application Laid-Open No. 2003-241092.
In accordance with a recent trend in high integration of a solid-state imaging device, a zoom lens system capable of obtaining a high contrast in even higher special frequency has been requested. However, it causes a problem that a conventional zoom lens system becomes larger in the diameter of a lens increasing the number of lens elements in order to increase optical performance.
In accordance with popularization in a digital camera, contradictory requests of portability (specifically, compactness and light weight) and a high zoom ratio are required to be satisfied at a time.
In the zoom lens system disclosed in Japanese Patent Application Laid-Open No. 2003-241092, although compactness and a wide angle of view are accomplished, the zoom ratio is about four or five, so that the request for a higher zoom ratio has not been satisfied.